Trial Shows Active Therapy Boosts Accommodative Amplitude

The Convergence Insufficiency Treatment Trial – Attention and Reading Trial (CITT-ART) shows, for what appears to be the first time in academic research, specific measures connecting improvements in convergence insufficiency deficits and connection vergence/accommodative therapy in pediatric patients, according to a report in Ophthalmic & Physiological Optics. 

Specifically, the study shows the therapy effectively improved accommodative function in participants with symptomatic convergence insufficiency and coexisting accommodative dysfunction compared with a randomized placebo control.

The inclusion criteria of CITT-ART closely matches the 2005 to 2009 Convergence Insufficiency Treatment Trial (CITT), although with updated benchmarks for decreased accommodative amplitude. CITT-ART introduces a longer course of treatment and adds 3 biocular therapy techniques. The study analyzes the progress of children 9 years to 14 years of age at 9 clinical centers, randomized into active therapy and placebo groups in a 2:1 ratio. Of 180 subjects with reduced accommodative amplitude, 115 participated in office-based vergence/accommodative therapy (OBVAT) and 65 in office-based placebo therapy. For the 108 children with decreased facility, 71 received OBVAT and 37 were assigned to the placebo group.

Examiners masked to the therapy assignment evaluated participants at 4, 8, 12, and 16 weeks of treatment, and children along with their parents were unaware of the therapy for which they were selected. Improvement in amplitude was measured in diopters (D), and facility was quantified with cycles per minute (cpm). In patients treated for accommodative amplitude with OBVAT, mean amplitude increased from 7.6 D to 16.2 D from baseline to week 16, and in the placebo group from 7.1 D to 12.2 D, according to the investigators. Further, for those with decreased facility receiving OBVAT, mean accommodative facility improved from 2.9 cpm to 16.4 cpm, and in the placebo group from 2.7 cpm to 10.3 cpm.

Certified therapists performed the standardized treatment protocol specific to each therapy group in 60-minute weekly sessions; including monocular, bi-ocular, and binocular exercises, plus assignment of homework tasks. Placebo therapy imitated the look and feel of active therapy. “For example, 1 placebo procedure involved viewing large letters through plano lenses, whereas an actual accommodative procedure involved viewing small letters through minus lenses,” the researchers wrote.

Vergence/accommodative therapy proved significantly effective to help subjects reach the normal accommodative amplitude of 14 D — 69% in OBVAT, compared with 32% in placebo therapy (P <.0001). In addition, meaningful improvements were also achieved toward the normal accommodative facility of 11 cpm; with 85% in OBVAT vs 49% in the placebo group (P <.0001). Average rate of improvement comprised the following:

• Accommodative amplitude rose by 1.5 D per week from baseline to week 4
• Amplitude rose by 0.2 D per week from weeks 4 to 16
• Accommodative facility increased by 1.46 cpm per week from baseline to week 4
• Facility increased at 0.63 cpm per week from weeks 4 to 16

A limitation of the trial involved an aspect of its population — children with convergence insufficiency were included for participation — but absent from the overall study were children with an accommodative dysfunction not affected by convergence insufficiency. Strengths of the trial included a standardized therapy protocol and high retention rate.

“Of the eventual 8.6 D mean improvement (in accommodative amplitude), 71% of that gain had occurred by the week 4 visit and 94% by the week 8 visit,” the researchers wrote. “In contrast, accommodative facility had improved by only 44% and 73% of its eventual mean gain of 13.5 cpm after 4 and 8 weeks of therapy, respectively.” 

Investigators suggest that 12 weeks of CITT-ART therapy may be optimal and effective.

Reference

Chen AM, Roberts TL, Cotter SA, et al. Effectiveness of vergence/accommodative therapy for accommodative dysfunction in children with convergence insufficiency. Ophthalmic Physiol Opt. Published online October 29, 2020/ doi: https://doi.org/10.1111/opo.12747